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Entry  Thu May 17 13:51:35 2018, Jon Richardson, Configuration, Electronics, Documentation & Schematics for AUX-PSL PLL 
    Reply  Fri May 18 14:18:03 2018, gautam, Configuration, Electronics, Basic MEDM Control Screen setup AUX_PLL_CTRL.png
       Reply  Mon May 21 15:34:19 2018, gautam, Configuration, Electronics, Channel hijacking history 
    Reply  Tue May 22 10:14:39 2018, Jon Richardson, Configuration, Electronics, Documentation & Schematics for AUX-PSL PLL Schematic_PLL.pdf
Message ID: 13858     Entry time: Thu May 17 13:51:35 2018     Reply to this: 13863   13876
Author: Jon Richardson 
Type: Configuration 
Category: Electronics 
Subject: Documentation & Schematics for AUX-PSL PLL 

[Jon, Gautam]

Attached is supporting documentation for the AUX-PSL PLL electronics installed in the lower PSL shelf, as referenced in #13845.

Some initial loop measurements by Gautam and Koji (#13848) compare the performance of the LB1005 vs. an SR560 as the controller, and find the LB1005 to be advantageous (a higher UGF and phase margin). I have some additional measurements which I'll post separately.

Loop Design

Pickoffs of the AUX and PSL beams are routed onto a broadband-sensitive New Focus 1811 PD. The AUX laser temperature is tuned to place the optical beat note of the two fields near 50 MHz. The RF beat note is sensed by the AC-coupled PD channel, amplified, and mixed-down with a 50 MHz RF source to obtain a DC error signal. The down-converted term is isolated via a 1.9-MHz low-pass filter in parallel with a 50 Ohm resistor and fed into a Newport LB1005 proportional-integral (PI) servo controller. Controller settings are documented in the below schematic. The resulting control signal is fed back into the fast PZT actuator input of the AUX laser.

Schematic diagram of the PLL.

 

 

 

 

 

 

 

 

 

 

Hardware Photos

Optical layout on the PSL table.

 

PLL electronics installed in the lower PSL shelf.

 

Close-up view of the phase detector electronics.

 

Slow temp. (left) and fast PZT signals into the AUX controller.

 

AUX-PSL beat note locked at 50 MHz offset, from the control room.

 

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